Up to now, as an ink-jet ink exhibiting good water resistance, there has been an ink which contains a water soluble dye dispersed or dissolved in a high boiling point solvent, and which contains a water soluble dye dissolved in a volatile solvent. However, a dye is inferior to a pigment in resistance characteristics such as light stability, and therefore ink using a pigment as a coloring agent has been required. But, it is difficult to disperse a pigment stably in an organic solvent, and it is also difficult to ensure stable dispersibility and ejection. On the other hand, in cases when ink using a high boiling solvent is applied onto a non-absorptive recording medium, a solvent in the ink is not volatized, results in difficulty of drying via evaporation of the solvent. Accordingly, ink using high boiling solvent cannot be printed on a non-absorptive recording medium.
Generally, ink using a volatile organic solvent can be properly printed onto a non-absorptive recording medium, due to adhesiveness of resin used and volatilization of the solvent. However, such ink, in which the volatile solvent is a major component, is easily dried at the nozzles of a recording head due to volatilization of the solvent, requiring frequent maintenance. Resistance of ink to some solvents may not be sufficient because the ink essentially requires good solubility in a solvent used.
Further, in an on-demand printer using a piezo element, usage of a large amount of a volatile solvent in ink increases frequency of maintenance, and also tends to cause problems of dissolution and swelling of members contacting the ink in the printer. In addition, a volatile solvent has numerous restrictions as a dangerous material under the Fire Defense Law. Consequently, in an on-demand printer using a piezo element, it is necessary to employ ink containing a volatile solvent in a small amount. However, components used in an actinic ray curable ink usually are ones having a relatively high viscosity. Therefore, it has been difficult to design ink having a viscosity capable of being ejected in conventional printers and further having good curability and high stability.
In order to overcome the problems described above, an actinic ray curable composition is disclosed in Japanese Patent O.P.I. Publication No. 2001-220526) which contains an epoxy compound, and a compound having an oxetane ring or a vinyl ether. Extensive study of the above actinic ray curable composition has been made, and, as a result, it has been proven that ink of this composition has problems in strength of a cured layer therefrom, ejection stability from nozzles, its adhesion to a recording medium, solvent resistance, and water resistance as well as in safety, stability, and curability under high humidity. Solution of the above problems has been desired.